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What can pass through that water can't?

Zeze

Zeze

Lifer
Drinking coke now and made me think. Once you break the cap seal, it'll go flat even if closed.

How does the carbonation gas escape the bottle when the liquid can't?

Also, are there materials (natural or artificial) that can hold water, but allow other things to permeate?
 
Glass can hold water, but allow light to pass through.

Everything depends on the molecular size of the container.
 
EagleKeeper said:
Glass can hold water, but allow light to pass through.

Everything depends on the molecular size of the container.
Click to expand...

I meant more 'physical' or 'tangible' things than light (let's not get anal here).

Let's say I create a precise material of mesh that's just fine enough to hold water. Can that precise mesh allow other things to filter, but water?
 
Zeze said:
I meant more 'physical' or 'tangible' things than light (let's not get anal here).

Let's say I create a precise material of mesh that's just fine enough to hold water. Can that precise mesh allow other things to filter, but water?
Click to expand...

If its sized to the molecule sure. Look at reverse osmosis systems, they've basically got a permeable membrane that only allows the "pure" water to get through.
 
deadlyapp said:
If its sized to the molecule sure. Look at reverse osmosis systems, they've basically got a permeable membrane that only allows the "pure" water to get through.
Click to expand...

Well it's easy to filter adulteration out of water. That's similar to sink trap capturing food debris.

I meant the other way around. Is there anything 'thinner' than water that can pass through such mesh that water can't?
 
Zeze said:
Drinking coke now and made me think. Once you break the cap seal, it'll go flat even if closed.

How does the carbonation gas escape the bottle when the liquid can't?

Also, are there materials (natural or artificial) that can hold water, but allow other things to permeate?
Click to expand...

Goretex/Omni-tech & associated products to name some of many. Watertight is almost always less sealing than air tight, although I'm sure some membrane could be designed that transports water molecules preferentially over air molecules.

*edit* Another obvious example is the cork in a wine bottle.
 
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As for pop, most likely the gas is not escaping the bottle.
What is happening is the gas escapes into the thin atmosphere that fills the top of the bottle, and then, when you open it, bye bye gas.

You'll also notice how much faster even a fairly new bottle will go flat, based on how much liquid remains. If you take most of the bottle out, reseal it, check in a few days... it'll be flat most likely. If you only take a few swigs, seal it and check back in a few days, it won't be nearly as flat, if much flatter at all.

Try this: once finished with your serving, before sealing the bottle completely, squeeze the sides until you have a deformed bottle that has very little "empty space" in the neck.
It won't go flat nearly as fast, in fact, if it's not opened but a few times, the carbonation will be fairly well preserved.

If it's a bad seal, gas could be escaping. But most of the time, that gas is simply waiting beneath the cap, longing to escape the bottle before you can enjoy the beverage. 😛
 
Zeze said:
Well it's easy to filter adulteration out of water. That's similar to sink trap capturing food debris.

I meant the other way around. Is there anything 'thinner' than water that can pass through such mesh that water can't?
Click to expand...

Probably not outside a chemistry lab: you'd have to get something with a smaller molecular size than water. Then, find a temperature and pressure where they both remain liquid.
 
If that confuses you, wait till you learn about building membranes.

We got vapor permeable, but air barrier; water barrier but vapor permeable; and a bunch of other shit. My mind's blown.
 
Zeze said:
Well it's easy to filter adulteration out of water. That's similar to sink trap capturing food debris.

I meant the other way around. Is there anything 'thinner' than water that can pass through such mesh that water can't?
Click to expand...

Sounds similar to a molecular sieve. The molecular sieve has tons of tiny pores. Molecules that are small enough can pass into pores while larger molecules can't. One application for these things is to separate water from alcohol.
 
I'm sure some gas is escaping the bottle, however I think the soda goes flat more due to the fact that it's no longer super concentrated, and carbonation is able to escape into the air in the bottle because the pressure inside the bottle is no longer as high as it was before the bottle was opened.
 
Zeze said:
Drinking coke now and made me think. Once you break the cap seal, it'll go flat even if closed.

How does the carbonation gas escape the bottle when the liquid can't?

Also, are there materials (natural or artificial) that can hold water, but allow other things to permeate?
Click to expand...

http://en.wikipedia.org/wiki/Permeation

the CO2 gas is under high pressure. the outside environment is at low pressure. eventually it will equilibrate.
 
Zeze said:
Drinking coke now and made me think. Once you break the cap seal, it'll go flat even if closed.

How does the carbonation gas escape the bottle when the liquid can't?

Also, are there materials (natural or artificial) that can hold water, but allow other things to permeate?
Click to expand...

the regular plastic 2 liter bottles are gas permeable. so even though the bottle is never opened it will eventually go flat.

edit: as for the bottle after opening it, take a look at the volume the gas has to come to equilibrium with before the bottle is ever opened, vs the volume after you've had a drink or two.

henry's law: http://www.800mainstreet.com/9/0009-006-henry.html
 
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destrekor said:
Try this: once finished with your serving, before sealing the bottle completely, squeeze the sides until you have a deformed bottle that has very little "empty space" in the neck.
It won't go flat nearly as fast, in fact, if it's not opened but a few times, the carbonation will be fairly well preserved.
Click to expand...
Not really. The vapour pressure from the CO2 will increase the volume anyway.
 
Zeze said:
Drinking coke now and made me think. Once you break the cap seal, it'll go flat even if closed.

How does the carbonation gas escape the bottle when the liquid can't?

Also, are there materials (natural or artificial) that can hold water, but allow other things to permeate?
Click to expand...

Carbonation does not escape the bottle. You released the pressure holding the CO2 in solution with the liquid, allowing the gas to perculate out of the liquid and mix with the air in the bottle. Buy a fizz saver pump to pressurize the bottle and your "fizz" will last and last.
 
WHAMPOM said:
Carbonation does not escape the bottle. You released the pressure holding the CO2 in solution with the liquid, allowing the gas to perculate out of the liquid and mix with the air in the bottle. Buy a fizz saver pump to pressurize the bottle and your "fizz" will last and last.
Click to expand...

pressurize or depressurize?
 
Yes, opening the bottle drops the pressure in the bottle, allowing more gas to leave the soda, even though you seal the bottle again.
 
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